The transgene contains a cDNA encoding the human p210 BCR-ABL1 fusion protein (B3A2 form; J:86227) under transcriptional control of the tetracycline-responsive element (tetO; also called TRE) fused to a minimal cytomegalovirus (CMV) promoter. In doubly transgenic mice expressing a tetracycline transactivator or reverse transactivator protein under the control of a ubiquitous or tissue-specific promoter, expression of the BCL-ABL1 fusion gene can be controlled temporally by withdrawal or administration, respectively, of a tetracycline analog.